Greg Fleming, a former Morgan Stanley executive, is turning the former Rockefeller family office into a financial services firm. He aims to increase the firm’s assets under management from $18.6 billion to $100 billion. The firm tacked on an investment firm focused on the ultra-wealthy in its first — but not its last — acquisition. Greg Fleming hasn’t been shy about his ambitions to turn what was the Rockefeller family office into a behemoth of a financial services firm.